Scientific derivation

How much polymer does paper technically need?

Paper and board contain polymer-based additives such as sizing agents and wet-strength agents, without which they would not have their properties. Six technical sources average 0.93 % of dry weight. Adding the scientifically recognised trace allowance of 0.1 % gives an overall threshold of 1.03 %. These additives are functionally necessary but do not form a plastic matrix of their own.

The derivation

0.93 %

average of the mean values from six technical sources (dry weight)

+ 0.10 %

scientifically recognised trace allowance

1.03 %

derived overall threshold

0.75 %

limit of the flustix LESS PLASTICS PRODUCT mark

Summary only

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What this is about

The question is how high the technically necessary polymer content in fibre-based packaging is according to the technical literature, and which threshold can be considered appropriate in regulatory terms if the recognised understanding of trace substances is also taken into account. The reference point is the Single-Use Plastics Directive (EU) 2019/904.

What is in paper, and what for

These are functional additives: polymer-based sizing agents for hydrophobicity such as alkyl ketene dimers (AKD) or alkenyl succinic anhydrides (ASA), wet-strength agents such as polyamide-epichlorohydrin resins (PAE), plus optical brighteners. They are added to the stock suspension or applied at the surface and are an integral part of established manufacturing processes.

The six sources

Francolini et al. (2023) 0.3–1.0 %, Bajpai (2015) 0.1–0.5 %, Hubbe (2006) 0.2–1.0 %, KTH (2023) 0.5–2.5 %, Gullichsen & Paulapuro (2000) 1.0–2.5 % and the Taschenbuch der Papiertechnik 0.4–1.2 %. The arithmetic mean of these mean values is 0.93 %.

Why a trace allowance

In environmental analysis, proportions below 0.1 % count as traces, a threshold found at the BfR (2018), the German Environment Agency (2020) and in the REACH Regulation. Add to that process variation and analytical uncertainty at very low polymer levels. The allowance is therefore a conservative addition, not leeway.

What the directive itself says

Recital 11 of the SUPD states that paints, inks and adhesives do not fall under the definition of plastic in Article 3(1). The European Commission’s guidelines confirm that functional additives such as adhesives, binders and paints are excluded from the scope. Polymer-based binders and additives in paper, board or cardboard that perform no structural function are therefore not covered by the SUPD.

Source: Six technical sources on paper technology (Francolini 2023, Bajpai 2015, Hubbe 2006, KTH 2023, Gullichsen/Paulapuro 2000, Taschenbuch der Papiertechnik 2021); BfR 2018; UBA 2020; REACH; Directive (EU) 2019/904, recital 11
As of: March 2026

Editorial responsibility: Malte Biss, Managing Director of flustix GmbH